The Sunday Times Rich List for 2003 includes 11 individuals and family groups from the Channel Islands.
According to the list, the Barclay twins are no longer the wealthiest people based in the Bailiwick.
Despite suffering losses of £30m, Guernsey-based David and Jonathan Rowland have managed to knock Sir David and Sir Frederick Barclay off the top spot, to become the richest people in the Channel Islands.
The Rowlands are said to have a combined wealth of £606m.
Their rise to the top of the Channel Islands rich list has been helped by a dramatic loss in the Barclay twins' fortune.
They have lost £180m over the past year, but are still worth £650m.
The pair operate their property, retail, media and hotel interests from a castle on their privately-owned island of Brecqhou, off the coast of Sark.